Have fun with some "Magical" LEDs you can switch on and off simply by shining a bright light from a keychain flashlight onto the LED. Please watch the video for a quick overview and then download and experiment with the Arduino Sketches using the links at the bottom of the page. The Sketches are, as follows:
LEDPhotodiodeTimer - use this code to determine the time delay needed for a particular type of LED
LEDPhotodiodeCandle - then, plug the value into this code to control a single LED
LEDPhotodiodeScanOnOff - next, use this code to control 8 LEDs you can independently switch on and off
LEDPhotodiodeScanDelay - finally, have fun with this code, which is for the last demo shown in the video